1. Field of the Invention
The present invention relates to a photochemical reaction apparatus which is applicable to the process of photochemical vapor deposition and more particularly to an apparatus for photochemically processing a silicon wafer placed in a reactive gas by the use of illuminating energy.
2. Description of the Prior Art
Included among the known manufacturing processes of semiconductor devices are semiconductor integrated circuits is a photochemical reaction process in which a silicon wafer is placed in a chamber filled with a reactive gas and an optical energy is vertically or horizontally projected onto the silicon wafer thereby etching the wafer or depositing a film on the wafer.
The gas contained in the chamber may be composed of Chlorine (Cl.sub.2) or the like in the case of photochemical reaction for wafer etching purposes and silane (SiH.sub.4) or the like in the case of photochemical reaction for the purpose of depositing a film on a wafer.
The chamber is provided with a window made of a glass material such as quartz for the purpose of externally introducing optical energy such as ultraviolet or far-ultraviolet beam into the chamber and preventing the flowing out of the gas within the chamber. Thus, there is the disadvantage of causing the deposition of an SiO.sub.2 film by photochemical reaction on the inner surface of the window during the projection of the optical energy and causing damage to the window by the photoetching. As a result, the transmittance of the window is deteriorated and the exposure efficiency is decreased thus necessitating frequent replacement of the window.
To overcome these deficiencies, attempts have been made so that N.sub.2 gas is blown to the window so as to make the window hardly stainable or the window is coated with an oil or the like so as to make it easy to remove the stain and these methods have been incapable of producing satisfactory effects.